The guy at the store was not correct. Hope that you figured out your problem after studying the exploded diagram of the CX2. In any event, the inner shaft and its gear are separate parts. A bad crash can mess up the gear in the way you described. If so, you simply replace the gear, EFLH1243. Repairing the CX2 is the most useful part of owning a CX2. It will teach you how to troubleshoot and repair helis.